Reversible galvanic battery.



Patented lune 3, |902.

T. A. Emwsou. REVERSIBLE GALVANIC BATTERY.

(Application filedv June 20, 1901.)

'Jin

(No Model.)

Witnesses Attys.

TH: Nonms PErzns co. PHcYauTHo., wAsn-uia'rom u, c.

UNITED STATES THOMAS A. EDISON, OF LLEWELLYN PATENT OFFICE.

PARK, NEWv JERSEY, ASSIGNOR TO EDISON STORAGE BATTERY COMPANY, ACORPORATION OF NEW JERSEY.

REVERSIBLE GAEVANIC BATTERY.

SPECIFICATION forming part of Letters Patent No. 701,804, dated June 3,1902.

Original application filed March l, 1901, Serial No. 49,453.

To @ZZ when@ it may concern:

Be it known that I, THOMAS A. EDISON, a citizen of the United States,and aresident of Llewellyn Park, in the county of Essex and State of NewJersey, have invented a certain new and useful Improvement in ReversibleGalvanic Batteries,(Oase No. 1,061,) of which the following is adescription.

The object of my present invention is to ro produce a reversiblegalvanicbattery of the type invented by me wherein insoluble active elements areemployed with a solution which remains unchanged during all condiv tionsof use, the battery being of great permanence and of remarkablylightweight per unit of power.

In batteries having alkaline electrolytes as commercially used, so faras I know, copper oxid has heretofore been employed exclusively as thedepolarizing material, the copper being reduced to the metallic state'upon discharging. The only other elements which have been suggested andwhich have been available as substitutes for copper in these batterieshave been those lower in the electrolytic series, such as mercury andsilver; but, so far as I know, 'these materials have not beensatisfactorily or commercially utilized on account of the difficultiesarising from 3o their application in'alkaline electrolytes, as well asbecause of their expense, especially in regard to silver, which metalpossesses the further disadvantage of being quite soluble in theelectrolyte when subjected tooxidation. I have sought by a greatmanyexperiments for an element or compound capable of being used in analkaline electrolyte, the heat of formation of whose oXid should be aslow or lower than that of oxid of mercury,Vv

4o and in this I have been successful, the result being the discovery ofan element for furnishing the oxygen to the oxidizable element ondischarge with even greater freedom than oXid of mercury, while at thesame time the new element is less expensive, is of less weight, is ofgreater permanency, and, n'ally, is of greater insolubility in theelectrolyte.

My improvedy oxygen-furnishing or depolarizing material may be employedin connec- Divided and this application iiled June 20. 1901. Serial (Nomodel.)

tion with any oxidizable element-such as V5o cadmium, copper, oriron-prepared, preferably, in special ways, as I shall describe.

My invention therefore consists of the combination of an electrolyte,such as apotassichydroxid solution, which remains unchanged 5 5 duringall conditions of working, and two elements therein insoluble in suchelectrolyte, the depolarizing element having for its active material anelectrolytically-active oXid of nickel or cobalt, preferably the former.

The invention further consists of the new depolarizer for use in anysuitable type of galvanic battery and which I deine in language ofvarying breadth in the appended The elements are preferably carried orsupported by hollow perforated plates, forming receptacles or pockets,which are illustrated in 'the accompanying drawings, forming part ofthis specification, and in which- Figure l is a face view of one of theplates having three pockets or receptacles, showing the front wallpartly broken away. Fig. 2 is a section on the line 2 2 of Fig. 1. Fig.3 is aplan showing two of the plates forming a 7 5 singlel combination,and Fig. 4 an enlarged detailed section.

In all of the above views corresponding parts are represented by thesame numerals yof reference. 8o

Each plate is formed with two walls 1 and ,f

2 constructed, preferably, of a single continuous sheet made,preferably, of very thin sheet-nickel-say about .005 of an inch inthicknessand bent at its bottom around a 85 horizontal frame 3, fromwhich extend the vertical spacing-frames 4 4, to all of which frames thesheet is secured by means of nickel rivets, as shown, to form a strongrigid hollow plate with pockets or receptacles between 9fthe verticalframesa 4. The walls l' and 2 of the plate, as shown, are perforatedwith i smallholes arranged very closely together and each aboutl .0l5'ofan inch in diameter.

I prefer to use nickel in the construction of 9 1 the plates, since thatmetal is not oxidizable by electric oxidation in an alkaline solution.Iron, on the other hand, is slightly oxidized under these conditions andis not so desirable, butif very carefully and perfectly plated withnickel it may be used satisfactorily for the construction of either theplates or the frames. Obviously the frames 3 and 4 may be and in someinstances preferably are constructed of hard rubber or other inertmaterial, to which the perforated sheet is riveted, as explained.Secured to one or both of the sides of the plate are a number ofinsulated spacingblocks 5 5 to prevent adjacent plates from touchingwhen immersed in the electrolyte.

Having described a suitable construction of supporting-plates or pocketsfor the active materials, reference will now be made to the preferredoxygen furnishing or storing element-fi. e., the depolarizer of thecell.

I have discovered by experiment that the hydrated lower oxids of nickeland cobalt when in contact with a conductorin an alkaline solution canbe almost wholly raised from this lower to a higher stage of oxidationelectrolytically than is possible by chemical means and that thesehigher oxids revert to a lower stage by reduction with extreme ease, andavailing myself of this fact I have constructed an oxygen storing ordepolarizing element capable of great capacity, of small weight, and ofhigh permanence. Neither the oxid of nickel nor of cobaltis appreciablysoluble in an alkaline electrolyte and both nickel and cobalt givenearly the same voltage in use; but since nickel is less expensive thancobalt I prefer to use the former element for the purpose.

A suitable process of making the oxygenstoring element consists in firstprecipitating either the monoxid or black hydrated dioxid of themetal-say nickel-in the usual way, washing the precipitate free from theproducts of the reaction, filtering off the liquid, and drying theprecipitate. The resulting dried hydrated oxid, which iselectrolytically active, is then powdered very fine and is ready forilse. Either oxid may be used with the same results. The process aboveoutlined applies to cobalt as well as to nickel. About seven parts, byweight, of the finely-powdered hydrate and three parts, by weight, ofHake graphite are then intimately mixed and moistened with a smallquantity of a strong solution of potassio hydroxid, so as to dampen themass, which is then inserted in the pockets or receptacles of the properplates in small quantities at a time and thoroughly tamped at eachaccession. Finally the mass is covered with a layer of asbestos (i, heldin place by a plate of nickel 7, secured in position by nickel wires S,threaded through openings near the top of the pockets. The plates thepockets of which are thus supplied with the mixture of theelectrolytically-active oxid and graphite are then immersed in asolution of potassio hydroxid in water and subjected for a considerabletime to an oxidizing current of about fifty milliamperes per square inchof surface, during which the oxid is either raised to a higher stage ofoxidation than the black peroxid (Ni203) or else acts as an absorber ofoxygen in some manner unknown to me. Whatever the action maybe the oxidso treated acts as a most eiiicient oxygen-storing element forcommercial use in agalvanic battery.

The object of employing graphite, which is not affected by electrolyticoxidation, is to offer a great extent of surface against which the wholeof the oxid is in contact, a large conducting-surface beingnecessary,since the electrolytic reduction and oxidation for practicalpurposes only extend a small distance from the conducting-surface,against which the oxid is in contact. This is admirably effected by theuse of graphite in its micaceous form, the proportions indicated beingsuch as to practically insure that the electrolytic action need notpenetrate a greater distance from the contact-surface than the thicknessof a single particle of the powdered oxid. Furthermore, there is nolocalaction between the nickel or cobalt oxids and the graphite.

The reason why nickel hydrate is preferably used instead of othercompounds of nickel is that the metal itself when nelydivided (asobtained by reducing a nickel compound by hydrogenor electrolysis) isnot oxidizable to any considerable extent when subjected to electrolyticoxidation in an alkaline solution. The sulfid of nickel is notdecomposed by electrolysis under the conditions of batterywork and thesulfid of cobalt only imperfectly. Hence the hydrates are the mostavailable compounds for use, since they do not become inert to the sameextent as hydrates of the oxids of iron after drying, they are easilyprepared, and by absorbing the s0- lution they swell within the pocketsor receptacles, so as to insure intimate contact and stability. Duringthe charging of the cell the absorption of oxygen by the oxid of nickelor cobalt causes the oxid to furtherswell and bulge the pockets orreceptacles outwardly, and on discharge a proportionate contractiontakes place. In order that the walls of the pockets or receptacles mayalways maintain the desirable intimate contact with the active material,the pockets are, as stated, made of some highly-elastic metal, such ashard-rolled sheet-nickel, so that at each contraction of the mass thepocket-walls will by their elasticity keep in contact therewith. Owingto the considerable changes in bulk to which the electrolytically-activeoxid of nickel or cobalt is subject, itis of importance that the lattershould be confined within conductingsupports which elasticallyaccommodate any variations of the mass. If the attempt were made toapply the oxid-for instance, as a paste to a conducting-plate or inother unconfined ways-the oxid in swelling and contracting would veryrapidly disintegrate, so as to become dislodged.

For the oxidizable element of my improved reversible cell I may employeither iron, cadmium,or copper, processes for the preparation IIO ofwhich will be described.V If iron is used,

\ I may follow the process described in my Patabout two parts, byweight, of flake-graphite.

of a size considerably larger than the perforations in the walls of thepockets or receptacles. Flakegraphite being exceedingly thin and oflarge area gives an extensive conducting-surface in proportion to itsbulk and weight. This mixture is then moistened with a twenty-per-cent.solution of potassio hydroxid, and the dampened mass is packed into thepockets or receptacles of theproper plates bya suitable tamping-tool.Owing to the want of flexibility of the graphite, the mixture packs to ahard porous mass'. The effect of electrolytic gassing, therefore, doesnot disintegrate the mass as a whole when properly compressed. Aftereach pocket or receptacle has been tightly packed with the mass almostto its top a wad of asbestos fiber 6 about a quarter of an inch inthickness is introduced into the pocket or receptacle above the mass,and on top of this packing is placed a strip of sheet-nickel 7, entirelycovering the asbestos and iilling the mouth of the pocket, which stripis permanently secured in position by nickel wires 8, threaded throughthe openings near the top of the pocket, as shown particularly in Fig. 2and as I have described in connection with the depolarizing electrode.The element thus formed is subjected to electrolytic oxidization in asolution of potassio hydroxid, wherebysulfur will be set free andcombining with the alkali forms a suliid ot' potassium, which diffusesout of the mass, While the iron is converted to a ferrous oxid, which isinsoluble in the solution and is electrolytically active. This diffusionof the alkaline suld out of the plate is hastened and facilitated bysubjecting the contents of the plate to alternate oxidization andreduction by alternately reversing the oxidizing-current, and by severalof these operations the whole of the sulfur will be eliminated and theelement will be ready for use after the iron has been reduced to themetallic state.

Since iron does not decompose water, there will obviously be no localaction between it and the graphite. The oxid formed from the sultidincreases in bulk and being intermediately mixed with the graphiteproduces considerable pressure on the walls ot' the plate, whichprevents any disturbance ot' the initial state of the mass even when itis subjected to strong gassing within the pores by overcharging theelementelectrically. The object of using the monosuliid is to secure thegreatest amount ot' iron oxid in the smallest space and in a formcapable of being reduced to the metallic state electrolytically.

Instead of employing electrolytically active finely-divided iron as theoxidizable element cadmium may be used for the purpose, as I describe inmyapplication for Letters Patent filed October 31, 1900, Serial No.34,994. When cadmium is used, it is preferably obtained by anelectrodeposition process, a very thin platina wire being used as thecathode, a plate of metallic cadmium as the anode, and a weak solutionof sulfate of cadmium as the electrolyte. By employing a strong currentin the electrolyte with a small platina wire as the cathode, asexplained, the cadmium will be deposited thereon in its metallic state,exceedingly finely divided and ilamentary in form and of great purity.The deposited finely-divided cadmium is detached from time to time fromthe cathode and is Washed in water to remove any adhering sulfate ofcadmium, Vafter which it may be packed in the pockets between the plates1 and 2, being held in position by a layer of asbestos 6 and a nickelcover 7, as explained in connection with the use of iron. When cadmiumis employed, its high conductivity makes it unnecessary to admix aflake-like conducting material with the cadmium, as is desirable withiron.

If copper is used as the oxidizable element instead of either iron orcadmium, it may be obtained as I describe in my application for LettersPatent filed on even date herewith, Serial No. 65,288, (Edison No.1,064,) by first reducing pure carbonate of copper in the usual way byhydrogen at the lowest possible temperature that will insure perfectreduction, after which the finely-divided copper so obtained issubjected in an open chamber to a temperature of not over 500 Fahrenheitfor six` or seven hours until the copper is converted into its blackoxid, (OuO.) This oxid is then mixed with i'lakegraphite or other in-Aert conducting material in the proportion of seven parts, by weight, ofthe oxid to three parts,by weight,of the iake-graphite and the mixturelightly packed .in the pockets or receptacles of the plates, beingsecured in place as described. `When subjected to the effect ofelect-rolytic reduction, the black oxidv will be reduced to the metallicform, and in the subsequent discharging operation the copper will beoxidized to the red oxid, (C1120.)

The two elements of the battery are preferably utilized in a solution oftwenty-five per cent. of potassio hydroxid in water, and the cell isready for use. When charged, the hydrated nickel or cobalt oxid will beraised to its superperoxid state, and the oxidizable elements (iron,cadmium, or copper) will be reduced to the metallic condition. YV henthe battery is discharged, the nickel or cobalt oxid will revert to alower stage, the iron (if used) will be raised to the ferrous conditionof oxidation, the cadmium (if used) will be raised to the oxid ofcadmium, and the copper (if used) will be raised to the red oxid,(Oligo.)

My improved. battery can be overcharged,

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fully discharged,or even reversed and charged in the opposite directionwithout any inj nry. Overgassingdoes not disturb the initial state ofthe materials in the pockets. All the ingredients are insoluble, thesupportingplates are unattacked by electrolytic oxidation, and the wholeoperation is independent of the strength of the solution, so that thebattery is of great permanence, While at the same time more energy willbe stored per unit of weight than with any other permanent practicalcombination heretofore suggested.

I have constructed a battery employing hydrated oxid of nickel andelectrolytically-active iron, as above described, which gives anavailable storage capacity of one-horse-power hour for seventy-threepounds weight; but it may be made lighter without destroying itspermanent character.

The specific magnetic metals are iron,nickel, and cobalt. By theexpression oxid of a specie magnetic metal other than ironas employed inmy claims I mean oxid of nickel, oxid of cobalt, or a combination ot'such oxids. By the use of that expression it is my purpose to embraceand both of these available oxids. I shall also specifically claim oxidof nickel herein, and I have specifically claimed oxid of cobalt in myapplication for Letters Patent filed March l, 1901, Serial No. 49,452.

I do not claim herein the specific combination of oxid of nickel orcobalt and electrolytically-active finely-divided iron or iron oxid, asthat combination is claimed in my application, Patent No. 678,722, datedJuly 16, 1901. I do not claim herein the specific combination of oxid ofnickel or cobalt and cadmium, as that specific combination is claimed inmy Patent No. 692,507, dated February 4, 1902, and I do not claim hereinthe specific combination of oxid of nickel or cobalt and copper, as thatspecific combination is claimed in my application tiled on even dateherewith, Serial No. 65,288; but

What I do claim, and desire to secure by Letters Patent, is as follows:

1. An active element for a reversible galvanic battery, comprising aconducting-support, an electrolytically-active oxid of a specic magneticmetal other than iron carried by said support, and a flake-like inertconducting material intimately mixed with said oxid, substantially asset forth.

2. An active element for a reversible galvanic battery, comprising aconducting-support, an electrolytically-active oxid of a specic magneticmetal other than iron carried by said support,and flake-graphiteintimately mixed with said oxid, substantially as set forth.

3. An active element for a reversible galvanic battery, comprising aconducting-support, an oxid of nickel carried thereby having more oxygenthan Ni203, like conducting material intimately mixed with said oxid,substantially as set forth.

include generically and an inert flake- 4. An active element for areversible gal- Vanic battery, comprising a conducting-support, an oxidof nickel carried therebyvhaving more oxygen than Ni203, andflake-graphite intimately mixed with said oxid, substantially as setforth.

5. An active element for a reversible galvanic battery, comprising aconducting-support, a hydrated oxid of nickel carried thereby, and aflake-like inert conducting material intimately mixed with said oxid,substantially as set forth.

6. An active element for a reversible galvanic battery, comprising aconducting-support, a hydrated oxid of nickel carried thereby, andiake-graphite intimately mixed with said oxid, substantially as setforth.

7. In a reversible galvanic battery, the combination of an electrolytewhich remains unchanged during all conditions of working, and twoelements therein insoluble in such electrolyte, the depolarizing elementhaving for its active material an electrolytically-active oxid of aspecific magnetic metal other than iron, substantially as set forth.

8. In a reversible galvanic battery, the comf bination of an electrolytewhich remains unchanged during all conditions of working, and twoelements therein insoluble in such electrolyte, the depolarizing elementhaving for its active material an electrolytically-active oxid of aspecic magnetic metal other than iron and in a condition of oxidationhigher than the peroxid state, substantially as set forth.

9. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of working, aconducting-support therein, an insoluble oxidizable material carried bysaid support, a second conducting-support employing a receptacle havingperforated walls, and a hydrated oxid of a specific magnetic metal otherthan iron carried Within said receptacle, substantially as set forth.

10. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all. conditions of Working, aconducting-support therein, an insoluble oxidizable material carried bysaid support, a second conducting-support, a hydrated oxid of a specificmagnetic metal other than iron carried by said second support, and aflake-like inert conducting material inti mately mixed with said oxid,substantially as set forth.

1l. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of workin g, aconducting-support therein, an insoluble oxidizable material carried bysaid support, a second conducting-support, a hydrated oxid of a specificmagnetic metal other than iron carried by said second support, andflake-graphite intimately mixed with said oxid, substantially as setforth.

12. In a reversible galvanic battery, the

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combination of an electrolyte which remains unchanged during allconditions of working, and two elements therein insoluble in suchelectrolyte, the depolarizing element having for its active material anelectrolytically-active oxid of nickel, substantially as set forth.

13. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of Working, aconducting-support therein, an insoluble oxidizable-material carried bysaid support, a second conducting-support, and an oxid of nickel carriedthereby having morev oxygen than Ni203, substantially as set forth.

14. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of workin g, aconducting-support therein, an insoluble oxidizable material carried bysaid support, a second conductingsupport employing a receptacle havingperforated Walls, and an oxid of nickel carried Within said receptacleand having more oxygen than Ni203, substantially as set forth.

15. In a reversible galvanicv battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of Working, acond uctin g-support therein, an insoluble oxidizable material carriedby said support',a second conducting-support, an oxid of nickel carriedthereby having more oxygen than Ni208, and an inert conducting materialintimately mixed with said oxid, substantially as set forth.

16. In a reversible galvanic battery, lthe combination of an alkalineelectrolyte which remains unchanged during all conditions of Working, aconducting-support therein, an insoluble oxidizable material carried bysaid support,a second conducting material,an oxid of nickel carriedthereby having more oxygen than NZOS, and an inert Hake-like conductingmaterial intimately mixed with said oxid, substantially as set forth.

17. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of Working, aconducting-support therein, an insoluble oxidizable material carried bysaid support, a second cond ucting-s'upport,an oxid of nickel carriedthereby having more oxygen than Ni203, and flake-graphite intimatelymixed with said oxid, substantially as set forth.

.18. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of Working, acond noting-support therein, an insoluble oxidizable material carried bysaid support,vasecond conducting-support, a hydrated oxid of nickelcarried thereby, and a flake like inert conducting material intimatelymixed with said oxid, substantially as set forth.

19. In a reversible galvanic battery, the combination of an alkalineelectrolyte which remains unchanged during all conditions of Working, acond noting-support therein, an insoluble oxidizable material carried bysaid support, a second conducting-support, a hydrated oxid of nickelcarried thereby, and flake-graphite intimately mixed with said oxid,substantially as set forth.

This specification signed and witnessed this 17th day of June, 1901.

THOMAS A. EDISON.

Wi tnesses FRANK L. DYER, RIoHD. N. DYER.

